The Dow Jones Industrial Average was down almost 200 points as of 10 a.m., or 1.2 percent. The S&P 500 and NASDAQ indexes were also down roughly 1 percent in early-morning trading.

A closely watched gauge of of business conditions—The Institute for Supply Management’s purchasing manager’s index—showed slowing expansion in the manufacturing sector. In addition, weak earnings from large American firms like Amazon have made some traders question the strength of the economy. “I’m really bearish and defensive at the moment,” Daniel Weston, a fund manager at Aimed Capital GmbH in Munich, told Bloomberg. “Amazon was a big concern because the earnings were a reflection on the consumer. I’m concerned about growth and inflation coming off, continuing to trend lower.”

The downturn follows a positive day for the stock market Thursday, with the S&P 500 gaining more than 1 percent.